Ordinarily, neutrophilic inflammation is an acute response that either resolves or transitions to a chronic lymphocytic process. However, in several lung diseases including sepsis induced acute lung injury, neutrophil-dominated inflammation persists throughout the course of the disease. Activation of the transcription factor NF-?B is a proximal trigger for neutrophilic inflammation, but factors responsible for termination of the neutrophilic response (or failure to do so) and initiations of the repair process are less clear. In normal human airway epithelial cells and in preliminary experiments in animals, we have evidence that termination of the inflammatory response in the lungs depends on selective increased production of the inhibitory isoform of the transcription factor C/EBP( called p20. The DNA binding sites for C/EBP( and NF-?B are in close proximity in the promoter region of several genes and interactions between the two factors results in synergistic enhancement of gene expression by the activator C/EBP( isoform and inhibition by the dominant negative inhibitory isoform (p20). As both experimental tools and potential therapeutics, we have developed two unique recombinant fusion proteins rendered cell permeable by inclusion of a membrane translocation sequence (MTS). One of these proteins (I?B(((N)-MTS) inhibits activation of NF-?B and the other (p20-MTS) delivers the inhibitor isoform of C/EBP( to cell nuclei. Our goal is to use these tools to elucidate the roles of the two transcription factors, NF-?B and C/EBP(, in the pathogenesis of endotoxin induced lung injury and the early phase of lung repair in a well established sheep model. Specifically, we aim to: 1) in anesthetized sheep, determine the early time course of NF-?B and C/EBP( activity in liver and lung following endotoxemia, relate these changes to measurements of lung function and cellular and biochemical responses, and determine the effects of intravenous delivery of either the inhibitor of NF-?B or of C/EBP( on the response to endotoxemia; 2) in chronically instrumented, unanesthetized sheep, determine effects of intravenous administration of either the inhibitor of NF-?B or the inhibitor of C/EBP( on sub-acute physiologic, cellular and biochemical responses to endotoxin and on the early phase of recovery of the lungs from endotoxin-induced injury; 3) in chronically instrumented, unanesthetized sheep, determine effects of aerosol administration of either inhibitor on the response to endotoxin and on the early phase of recovery of the lungs from injury; and 4) from the above studies, select the most promising therapeutic regimen and determine effects of its administration four hours after endotoxemia on the subsequent course of the endotoxin response in chronically instrumented unanesthetized sheep. [unreadable] [unreadable] [unreadable] [unreadable] [unreadable]